Improving information dissemination in sparse vehicular networks by adding satellite communication

Information dissemination in pure Vehicular Ad Hoc NETworks (VANETs) such as ITS-G5 becomes problematic when the network is sparse. In situations where the number of vehicles, that can act as a communication node, is insufficiently low, e.g. in rural areas, during night-time or because of a low market penetration of the technology in the early years of market introduction, certain range limits (unavailability of for- warding nodes) or timing limits (store-and-forward techniques) are stressed. Due to the limited communication range, VANETs start to build separated clusters, if the density of equipped vehi- cles is too low. Consequently, information dissemination without delay-massive store-and-forwarding is only possible within one cluster, but not beyond. This paper investigates the integration of Car-to-Car (C2C) with an additional satellite communication technology, referred to as Car-to-Satellite (C2S). A realistic sparse vehicular network scenario has been simulated and evaluated with respect to the in-time reception of safety-related information. The results show that information dissemination can be significantly improved through a limited number of ve- hicles which are additionally equipped with satellite terminals. In fact, even the market introduction of VANET-based ITS can be significantly accelerated with just a few vehicles equipped with non-VANET communication technology.